4.7 Hydrology and Water Quality - City of Sacramento

4. Environmental Setting, Impacts, and Mitigation Measures

4.7 Hydrology and Water Quality

Sacramento Entertainment and Sports Center & 4.7-1 ESA / 130423 Related Development December 2013

Draft Environmental Impact Report


This section of the EIR evaluates potential environmental effects related to hydrology and water quality that would result with implementation of the Proposed Project. The analysis addresses surface water, groundwater, flooding, stormwater, and water quality.

Comments on the NOP from the Department of Toxic Substances Control (DTSC) requested that the EIR for the Proposed Project consider the South Plume, a groundwater plume contaminated with metals, solvents, and petroleum-based compounds located below a portion of the Downtown project site.1 Impacts associated with the South Plume are addressed in section 4.6, Hazards and Hazardous Materials.

The analysis included in this section was developed based on project-specific construction and operational features; data provided in the City of Sacramento 2030 General Plan; City of Sacramento 2030 General Plan Master Environmental Impact Report; several reports published by the California Department of Water Resources; the California Water Code and Code of Federal Regulations; the Water Quality Control Plan for the Sacramento and San Joaquin River Basins2; several National Pollutant Discharge Elimination System permits; Federal Emergency Management Agency Digital Flood Insurance Rate Maps and flood zone designation definitions; the American River Watershed Sanitary Survey 2008 Update, Sacramento County Multi-Hazard Mitigation Plan; Sacramento Groundwater Authority Basin Management Report Update; Stormwater Quality Improvement Plan for the County of Sacramento and the Cities of Sacramento, Citrus Heights, Elk Grove, Folsom, Galt, and Rancho Cordova; and the Stormwater Quality Design Manual for the Sacramento and South Placer Regions.

4.7.1 Environmental Setting

Surface Water3

The City of Sacramento is located at the confluence of the Sacramento and American rivers within the Sacramento River Basin. The Sacramento River Basin encompasses approximately 27,000 square miles and is bounded by the Sierra Nevada to the east, the Coast Ranges to the west, the Cascade Range and Trinity Mountains to the north, and the Sacramento – San Joaquin Delta (Delta) to the southeast. The Sacramento River Basin is the largest river basin in California, capturing, on average, approximately 22 million acre-feet of annual precipitation. The Sacramento River is approximately 327 miles long, and its major tributaries are the Pit and McCloud Rivers, which join the Sacramento River from the north, and the Feather and American Rivers, which are tributaries from the east. Numerous additional tributary streams and creeks flow from the east and west. The Sacramento Valley portion of the basin contains the largest

1 ERM, 2013. Final Draft Remedial Action Plan, Central Shops Study Area – Soil and South Plume Study Area –

Groundwater, Sacramento, California. January 2013. Figure 1-2. 2 Central Valley Regional Water Quality Control Board, 2011. Water Quality Control Plan for the Sacramento and

San Joaquin River Basins. October 2011. pp. II-5.00-II-8.00. 3 City of Sacramento, 2009. Sacramento 2030 General Plan Master Environmental Impact Report (SCH No.

2007072024). Certified March 3, 2009. pp. 6.7-1 – 6.7-2.





population, concentrated in the cities of Sacramento, West Sacramento, Chico, Red Bluff, and Redding. The river is regulated by Shasta Dam and several dams on the major tributaries, including Oroville Dam on the Feather River and Folsom Dam on the American River, which provide power generation, flood control, water supply, recreation, fisheries, and wildlife management.

Six small tributaries of the Sacramento River run through the greater Sacramento area and provide drainage for the City of Sacramento. These tributaries are Dry Creek, Magpie Creek, and Arcade Creek in the northern portion of the City (north of the American River), and Morrison Creek, Elder Creek, and Laguna Creek in the southern portion of the City (south of the American River). Forty miles south of the Sacramento area, the Sacramento and San Joaquin rivers meet and drain into the San Francisco Bay. Local surface water drainages or creeks such as Chicken Ranch and Strong Ranch sloughs, Florin Creek, Unionhouse Creek, Strawberry Creek, and Rio Linda Creek are additional major natural drainages tributary to the Sacramento River. Human-made drainage canals, such as Steelhead Creek (also referred to as the Natomas East Main Drain Canal) and the East, West, and Main Drainage canals provide drainage for a large portion of the urbanized areas within the City of Sacramento that are not served by the City combined sewer system (CSS) or the City storm drainage collection system.

The American River watershed encompasses approximately 1,900 square miles and is tributary to the Sacramento River. The American River watershed is situated on the western slope of the Sierra Nevada mountain range, extending from the spine of the Sierra Nevada westward to the City of Sacramento. The American River watershed drains approximately 2.7 million acre-feet annually. The river is regulated by dams, canals, and pipelines for power generation, flood control, water supply, recreation, fisheries, and wildlife management. Folsom Dam, located on the American River, is owned and operated by the U.S. Bureau of Reclamation. Folsom Lake and its afterbay, Lake Natoma, release water to the lower American River and to the Folsom South Canal. The operation of Folsom Dam directly affects most of the water utilities on the American River system.

Precipitation in Sacramento occurs primarily as rain from November through March. Climate data collected from 1941 through 2003 show that annual rainfall averaged 17.22 inches, but was variable. Recorded annual rainfall has ranged from a low of 6.25 inches in 1976 to a high of 33.44 inches in 1983. The American River watershed climate is temperate and is characterized by wet winters and dry summers; 95 percent of the annual precipitation occurs between November and April as both rain and snow at higher elevations. Flows in the Sacramento and American rivers are influenced by the volume of surface runoff within the respective watersheds, rainfall, the operation of upstream dams, Sierra Nevada spring snowmelt, local groundwater, and tidal action, which extends to the upper extent of the Delta in the Sacramento River at the I Street Bridge, just downstream of the confluence with the American River.

The Downtown project site is located approximately 1,000 feet east of the Sacramento River and just over one mile southeast of the Sacramento and American River confluence, and 0.3 miles to the west-northwest of the Sacramento River. Stormwater runoff from the project site is conveyed to Storm Drainage Basin 52. Please refer to section 4.11, Utilities and Service Systems, for a detailed description of Storm Drainage Basin 52.





Groundwater

The Downtown project site and six of the proposed offsite digital billboard sites are located within the South American Groundwater Subbasin of the Sacramento Valley Groundwater Basin, as delineated in the California Department of Water Resources (DWR) Bulletin 118 (2003 Update). The South American Subbasin encompasses 388 square miles, and is bounded on the east by the Sierra Nevada, the Sacramento River to the west, American River to the north, and south by the Cosumnes and Mokelumne rivers. The calculated groundwater storage capacity of the South American Subbasin is 4,816,000 acre-feet.4 The Central Sacramento County Groundwater Basin has nearly the same boundaries as the South American Subbasin and differs in places because the Central Sacramento County Groundwater Basin boundaries were drawn to be consistent with the Integrated Groundwater Surface Water Model (IGSM) for Sacramento County. The calculated long-term average annual sustainable yield from the Central Sacramento County Groundwater Basin in 273,000 acre-feet per year.5 Four of the offsite digital billboard sites are located within the North American Subbasin, which encompasses 548 square miles and is bounded by the Bear River to the north, Feather River to the west, Sacramento River to the south, and a line that extends between the Bear River and Folsom Lake.6

Sacramento is underlain by various geologic formations. These formations include an upper, unconfined aquifer system7 consisting of the Modesto, Riverbank, Turlock Lake, Victor, Fair Oaks, and Laguna Formations, and Arroyo Seco and South Fork Gravels, and a lower, semi-confined aquifer system consisting primarily of the Mehrten Formation. These deposits form a wedge that generally thickens from east to west to a maximum thickness of about 2,500 feet along the western margin of the subbasins. Groundwater occurs in unconfined to semi-confined states throughout the subbasins. Semiconfined conditions occur in localized areas; the degree of confinement typically increases with depth below the ground surface. Groundwater in the upper aquifer formations is typically unconfined. However, due to the mixed nature of the alluvial deposits, semi-confined conditions can be encountered at shallow depths in the upper aquifer.

Groundwater depths at wells in the vicinity of the City of Sacramento in the South American Subbasin have fluctuated generally less than 10 feet overall since the mid-1970s.8 In the North American Subbasin, groundwater levels have generally remained stable and between 20 and 35 feet below mean sea level (msl), fluctuating no more than five feet since 1997.9 Depth to groundwater beneath the Downtown project site varies seasonally, and has been reported to range from 7.5 to 29 feet below ground surface, and 7.5 to 9 feet below the ESC site.10 According to the 4 California Department of Water Resources, 2004. California’s Groundwater Bulletin 118, Sacramento Valley

Groundwater Basin, South American Subbasin. February 27, 2004. p. 1. 5 Water Forum, Sacramento County Water Agency, and MWH, 2006. Central Sacramento County Groundwater

Management Plan. February 2006. pp. 2-22 – 2-23 6 California Department of Water Resources, 2006. California’s Groundwater Bulletin 118, Sacramento Valley

Groundwater Basin, North American Subbasin. January 20, 2006. p. 1. 7 An unconfined aquifer is one that is open to receive water from the surface. A confined aquifer is overlain by a rock

layer that prevents water from the surface from percolating into the aquifer. 8 Central Valley Regional Water Quality Control Board, 2011. Water Quality Control Plan for the Sacramento and

San Joaquin River Basins. October 2011. pp. II-5.00-II-8.00. 9 Sacramento Groundwater Authority, 2011. Basin Management Report Update 2011. Undated. pp. 14-15. 10 Geocon Consultants, Inc. 2013. Geotechnical Investigation, Sacramento Entertainment and Sports Center.

November. p. 7 and Figure 2.





groundwater elevation contour map included in the Central Sacramento County Groundwater Management Plan, groundwater elevations at the offsite digital billboard sites range from 35 feet below msl at the Business 80 at Del Paso Regional Park/Haggin Oaks and I-80 at Roseville Road sites to approximately 5 feet above msl at the I-5 at Bayou Road site.11

Groundwater containing elevated levels of contaminants are present within the Sacramento region, including below the Downtown project site. Additionally, there are currently over 200 active Leaking Underground Storage Tank (LUST) locations within the City of Sacramento. In the greater region, polluted groundwater plumes emanate from the former McClellan Air Force Base (AFB), the former Mather AFB, and the Aerojet property south of Highway 50 in Rancho Cordova.12 A portion of the South Plume, a groundwater plume originating in the Railyards and contaminated with metals, solvents, and petroleum-based compounds, is located below a portion of the Downtown project site.13 Impacts related to contaminated groundwater are addressed in section 4.6, Hazards and Hazardous Materials. While there are instances of polluted groundwater in the region, groundwater quality in the Sacramento area is generally within the secondary drinking water standards for municipal use, including levels of iron, manganese, arsenic, chromium, and nitrates.14

There is currently a dewatering system at the Downtown project site that includes pumps in each of the parking garages. The exact volume of groundwater that is pumped from the parking garages is unknown, but is estimated at an average of approximately 15.1 million gallons per month.15 The water pumped from the parking garages is discharged to the CSS connection on L Street.

Flooding

The following discussion is based primarily on information provided in the City of Sacramento General Plan Master EIR.16

Background

High water levels along the Sacramento and American rivers are a common occurrence in the winter and early spring months due to increased flows from stormwater runoff and/or snowmelt. To protect the area from regional flooding, an extensive system of dams, levees, overflow weirs, drainage pumping stations, and flood control bypass channels are strategically located on and adjacent to the Sacramento and American rivers, and their respective tributaries. In the project

11 Water Forum, Sacramento County Water Agency, and MWH, 2006. Central Sacramento County Groundwater

Management Plan. February 2006.pp. 2-22 – 2-23 12 City of Sacramento, 2009. Sacramento 2030 General Plan Master Environmental Impact Report (SCH No.

2007072024). Certified March 3, 2009. p. 6.7-9. 13 ERM, 2013. Final Draft Remedial Action Plan, Central Shops Study Area – Soil and South Plume Study Area –

Groundwater, Sacramento, California. January 2013. Figure 1-2. 14 City of Sacramento, 2009. Sacramento 2030 General Plan Master Environmental Impact Report (SCH

No. 2007072024). Certified March 3, 2009. p. 6.7-8. 15 Hiser, Matt, 2013. Personal communication via email between Brian Boxer of ESA and Matt Hiser of Turner

Construction. December 11, 2013. 16 City of Sacramento, 2009. Sacramento 2030 General Plan Master Environmental Impact Report (SCH

No. 2007072024). Certified March 3, 2009. pp. 6.7-9 – 6.7-12.





vicinity, the amount of water flowing through the levee system can be controlled by Folsom Dam on the American River and the reserve overflow area of the Yolo Bypass on the Sacramento River. However, several areas of the City remain vulnerable to localized flooding by the overtopping of rivers and creeks, levee failures, and the surcharge of urban drainage systems that cannot accommodate large volumes of water during severe rainstorms.17

During major flood events, high flows can occur throughout the Sacramento River and American River systems. The relative timing of these flows can accentuate the flood risk because high water levels in a primary stream (Sacramento River) can result in a "backwater" effect, which reduces the effective capacity of the tributary or incoming stream (American River). This is true in rivers and streams and stormwater collection systems. The historic peak flow on record for the gage located on the Sacramento River at the I Street Bridge is 108,800 cubic feet per second (cfs) during the 1986 flood. While areas in the City and surrounding communities did experience some localized flooding, the Sacramento River at I Street remained four inches below flood stage during that event.

Riverine flooding occurs when a watercourse exceeds its ‘bank-full’ capacity and is the most common type of flood event in the Sacramento River Basin. Riverine flooding occurs as a result of prolonged rainfall that is combined with saturated soils from previous rain events, or combined with snowmelt, and is characterized by high peak flows of moderate duration and by a large volume of runoff. Riverine flooding occurs in river systems with tributaries that drain large geographic areas and can include many watersheds and sub-watersheds. The duration of riverine floods varies from a few hours to many days. Factors that directly affect the amount of flood runoff include precipitation amount, intensity, and distribution; soil moisture content; channel capacity; seasonal variation in vegetation; snow depth; and water-resistance of the surface. In Sacramento County, riverine flooding typically occurs anytime from November through April. Flooding is more severe when previous rainfall events saturate ground conditions. Urbanization may increase peak flow runoff as well as the total volume of stormwater runoff from a site. The increase is dependent upon the type of soil and topography compared to the proposed land uses.

Floodplain Management

The Federal Emergency Management Agency (FEMA) administers the National Flood Insurance Program (NFIP) and delineates areas subject to flood hazards on Flood Insurance Rate Maps (FIRMs) for each community participating in the NFIP. The FIRMs show the areas subject to inundation by a flood that has a one percent chance or greater of being equaled or exceeded in any given year. This type of flood is referred to as the 100-year or base flood. Areas on FIRMs are divided into geographic areas, or zones, that FEMA has defined according to varying levels of flood risk. Table 4.7-1, FEMA Flood Zone Designations, includes a description of the risk associated with each zone.

17 Sacramento County, 2011. Sacramento County, California, Local Hazard Mitigation Plan. September 2011. p. 4.4.





TABLE 4.7-1FEMA FLOOD ZONE DESIGNATIONS

Zone Description

Moderate to Low Risk Areas B and X (shaded) Area of moderate flood hazard, usually the area between the limits of the 100-year and 500-year

events. Are also used to designate base floodplains of lesser hazards, such as areas protected by levees from 100-year event, or shallow flooding areas with average depths of less than one foot or drainage areas less than 1 square mile.

C and X (unshaded) Area of minimal flood hazard, usually depicted on FIRMs as above the 500-year flood level.

High Risk Areas A Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life of a 30-

year mortgage. Because detailed analyses are not performed for such areas; no depths or base flood elevations are shown within these zones.

AE The base floodplain where base flood elevations are provided. AE Zones are now used on new format FIRMs instead of A1-A30 Zones.

A1-30 These are known as numbered A Zones (e.g., A7 or A14). This is the base floodplain where the FIRM shows a BFE (old format).

AH Areas with a 1% annual chance of shallow flooding, usually in the form of a pond, with an average depth ranging from 1 to 3 feet. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Base flood elevations derived from detailed analyses are shown at selected intervals within these zones.

AO River or stream flood hazard areas, and areas with a 1% or greater chance of shallow flooding each year, usually in the form of sheet flow, with an average depth ranging from 1 to 3 feet. These areas have a 26% chance of flooding over the life of a 30-year mortgage. Average flood depths derived from detailed analyses are shown within these zones.

AR Areas with a temporarily increased flood risk due to the building or restoration of a flood control system (such as a levee or a dam). Mandatory flood insurance purchase requirements will apply, but rates will not exceed the rates for unnumbered A zones if the structure is built or restored in compliance with Zone AR floodplain management regulations.

A99 Areas with a 1% annual chance of flooding that will be protected by a Federal flood control system where construction has reached specified legal requirements. No depths or base flood elevations are shown within these zones.

Undetermined Risk Areas D Areas with possible but undetermined flood hazards. No flood hazard analysis has been

conducted. Flood insurance rates are commensurate with the uncertainty of the flood risk.

SOURCE: Federal Emergency Management Agency, 2013. Definitions of FEMA Flood Zone Designations.

https://msc.fema.gov/webapp/wcs/stores/servlet/info?storeId=10001&catalogId=10001&langId=-1&content=floodZones&title=FEMA%2520Flood%2520Zone%2520Designations. Accessed October 12, 2013.

As shown in Figure 4.7-1, two types of the FEMA Flood Zone Designation X apply to the project site. Generally, the southern portion of the site as well as the length of 5th Street within the site is designated Zone X (unshaded) – areas above the 500-year flood zone. The remainder of the site is designated Zone X – (shaded) above the 100-year zone with reduced flood risk due to levees. There is an approximately nine foot difference in elevation between L and J streets, and the portion of the site that is located outside of the 500-year flood zone is at a higher elevation than the remainder of the site.

Each potential offsite digital billboard location is described in Chapter 2, Project Description. Table 4.7-2 presents the FEMA Flood Zone Designation that applies to each offsite digital billboard location as well as the distance from each offsite digital billboard site to the nearest river. Offsite digital billboard locations 1 through 7 and 10 are either outside of any flood hazard

Capitol Mall

K St

J St

H St

I St

L St

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4th

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5th

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6th

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7th

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8th

St

9th

St

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2nd

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Riv

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Project Boundary

FEMA FLOOD ZONES

100-Year Flood Zone (AE)

Above 500-Year Flood Zone (X)

Above 500-Year Zone (X)* *Area w/Reduced Flood Risk Due to Levee

0 500

Feet

Figure 4.7-1FEMA Flood Zones

Sacramento Entertainment and Sports Center & Related Development EIR . 130423SOURCE: FEMA, 2012; Microsoft, 2012; City of Sacramento, 2012; ESA, 2013

4.7-7





TABLE 4.7-2FEMA FLOOD ZONE DESIGNATIONS AT OFFSITE DIGITAL BILLBOARD SITES

Site Name FEMA Flood Zone Designation

1. I-5 at Water Tank Zone X, Area with Reduced Flood Risk Due to Levee

2. US 50 at Pioneer Reservoir Outside of any flood zone

3. Business 80 at Sutter’s Landing Regional Park

Zone X, Area with Reduced Flood Risk Due to Levee

4. Business 80 at Del Paso Regional Park/Haggin Oaks

Zone X, Area of Minimal Flood Hazard

5. Business 80 at Sutter’s Landing Regional Park/American River

Zone X, Area with Reduced Flood Risk Due to Levee

6. I-80 at Roseville Road Zone X, Area of Minimal Flood Hazard

7. SR 99 at Calvine Road Zone X, 0.2% Annual Chance Flood Hazard

8. I-5 at Bayou Road Zone AE

9. I-5 at San Juan Road Zone AE

10. I-5 at Sacramento Railyards Zone X, Area of Minimal Flood Hazard

SOURCE: Federal Emergency Management Agency, 2012. FEMA Mapping Information Platform, Flood Hazard Zones GIS data layer.

See Figure 4.7-1 of this EIR. August 16, 2012.

zone or within Zone X. The I-5 at Bayou Road and I-5 at San Juan billboard sites are located within Zone AE, a zone that applies to the 100-year floodplain where base flood elevations, or the water surface elevations associated with the 100-year event, are also available. None of the offsite digital billboard locations are located within a designated floodway, which is defined as the channel of a water course and those portions of the adjoining floodplain required to provide for passage of a selected flood with a small increase in flood stage above that of natural conditions.18

The Sacramento Area Flood Control Agency (SAFCA) was formed to address the Sacramento area’s vulnerability to catastrophic flooding. This vulnerability was exposed during the record flood of 1986 when Folsom Dam exceeded its normal flood control storage capacity and several Sacramento area levees nearly collapsed under the strain of the storm. In response, the City of Sacramento, the County of Sacramento, Sutter County, the American River Flood Control District, and Reclamation District 1000 created SAFCA through a Joint Exercise of Powers Agreement to provide the Sacramento region with increased flood protection along the American and Sacramento rivers and their immediate tributaries. The SAFCA mission is to provide the region with at least a 100-year level of flood protection as quickly as possible while seeking a 200-year or greater level of protection over time. Under the Sacramento Area Flood Control Agency Act of 1990, the California Legislature has given SAFCA broad authority to finance flood control projects and has directed the Agency to carry out its flood control responsibilities in ways that provide optimum protection to the natural environment. Current SAFCA projects include the Folsom Dam Joint Federal Project, American River Common Features Project, Natomas Levee Improvement Program, South Sacramento Streams Project, Mayhew Levee Improvements Project, and Sacramento Bank Protection Project.

18 California Department of Water Resources, 2013a. Designated Floodway Web Viewer. http://gis.bam.water.ca.gov/

bam/. Accessed October 12, 2013.





After Hurricane Katrina, the U.S. Army Corps of Engineers (USACE) developed more stringent levee standards. As of August 31, 2013, the USACE 100-year storm event certification for portions of the lower Sacramento and American River levees expired. In the vicinity of Downtown Sacramento, a portion of the Sacramento River East Levee starting near Front and R streets and extending approximately 3.7 miles downstream was decertified. SAFCA is working toward implementing levee improvements and applying for re-certification of the levees under FEMA NFIP standards and the California Urban Levee Design Criteria. In early 2014, SAFCA plans to have identified specific improvements necessary for meeting FEMA standards for levee certification, will make recommendations to its Board, and then develop a plan for implementation.19 FEMA Flood Zone Designations at the Downtown project site and offsite digital billboard sites have not been changed as a result of the expiring levee certifications. FEMA currently does not have a schedule for remapping these areas.

Within the Sacramento region, 30,000 acres are protected from the 100-year flood by levees, and 18,000 acres are within the 100-year floodplain. In February 1996, the City prepared the Comprehensive Flood Management Plan to better protect citizens and property from major flood events. The Comprehensive Flood Management Plan was conceived as an implementation tool for the City Council to use in planning for future modifications to policies and ordinances to enhance the level of flood protection in the City. Further, SAFCA has outlined a plan to provide a 200-year level of flood protection to the Sacramento area. Other floodplain planning efforts have been implemented by SAFCA and Reclamation District No. 1000 through a variety of joint agreements with federal, state, and local agencies. These agreements have resulted in the planning of improvements to flood protection structures (e.g., levees, canals), ecosystem protection and restoration, and the sharing and updating of floodplain management information with all involved parties to the agreements, including the City. In 2007, the passage of Senate Bill 5 effectively set a higher flood protection threshold for urban areas, including Sacramento, by requiring a minimum of 200-year protection.20 Additional information about this requirement is provided under Regulatory Setting below.

The City of Sacramento has implemented a capital improvement program that includes improvement of stormwater drainage facilities within the City to improve localized flooding conditions and capacity in the system. section 4.11, Utilities and Service Systems, includes a description of planned improvements.

Water Quality

Surface Water

Ambient water quality in the Sacramento and American rivers is influenced by numerous natural and artificial sources, including soil erosion, discharges from industrial and residential wastewater plants, stormwater runoff, agriculture, recreation activities, mining, timber harvesting

19 Sacramento Regional Flood Control Agency, 2013. Levee Certification. http://www.safca.org/Levee_

Certification.html#. Accessed October 24, 2013. 20 California Water Code. Central Valley Flood Protection, Section 9600 – 9651.





in upper portions of the watersheds, flora, and fauna. Table 4.7-3 shows water bodies in the urbanized Sacramento area that are considered impaired because water quality standards are exceeded.21 The reaches of the Sacramento and American rivers that flow through the Sacramento urban area are considered impaired for certain fish consumption and aquatic habitat and are listed on the U.S. Environmental Protection Agency (EPA) approved 2010 section 303(d) list of impaired water bodies. The Sacramento and American rivers are both listed as impaired under the 303(d) list for mercury and unknown toxicity. Other major creeks, drainage canals, and sloughs in the City boundaries are also listed for pesticides and copper.

TABLE 4.7-3LOCAL WATERBODIES EXCEEDING WATER QUALITY STANDARDS

Waterbody Reach Estimated Size Affected Pollutant/Stressor(s)

Sacramento-San Joaquin Delta

-- 41,746 acres Chlordane, DDT, Dieldrin, Dioxin Compounds, (including 2,3,7,8-TCDD), Exotic Species, Furan Compounds, Mercury, Nickel, PCBs (Polychlorinated biphenyls), PCBs (dioxin-like), Selenium

American River (Nimbus Dam to confluence with Sacramento River)

Lower 27 miles Mercury

Arcade Creek -- 9.9 miles Chlorpyrifos, Diazinon, Copper

Morrison Creek Morrison Creek from Elk Grove-Florin Rd to Beach Lake

26 miles Chlorpyrifos, Diazinon

Elder Creeek -- 11 miles Chlorpyrifos, Diazinon

Elk Grove Creek -- 6.9 miles Chlorpyrifos, Diazinon

Strong Ranch Slough -- 6.4 miles Chlorpyrifos, Diazinon

Chicken Ranch Slough -- 8 miles Chlorpyrifos, Diazinon

Lake Natoma -- 485 acres Mercury

Steelhead Creek (Natomas East Main Drainage Canal)

(downstream of confluence with Arcade Creek)

3.5 miles Diazinon, PCBs

Steelhead Creek (Natomas East Main Drainage Canal)

(upstream of confluence with Arcade Creek)

12 miles PCBs

Sacramento River Knights Landing to the Delta

16 miles Mercury, Diazinon, Unknown Toxicity

SOURCE: City of Sacramento, 2009. Sacramento 2030 General Plan Master Environmental Impact Report (SCH No. 2007072024).

Certified March 3, 2009. p. 6.7-6.

Constituents found in urban runoff vary as a result of differences in rainfall intensity and occurrence, geographic features, the land use of a site, as well as vehicle traffic and percent of impervious surface. In the Sacramento area, there is a natural weather pattern of a long dry period from May to October. During this seasonal dry period, pollutants contributed by vehicle exhaust, vehicle and tire wear, crankcase drippings, spills, and atmospheric fallout accumulate within the 21 Impaired is defined as having chronic or recurring monitored violations of the applicable numeric and/or narrative

water quality criteria.





urban watershed. Precipitation during the early portion of the wet season washes these pollutants into the stormwater runoff, which can result in elevated pollutant concentrations in the initial wet weather runoff if not properly intercepted and managed.

Beneficial uses are designated by the Central Valley Regional Water Quality Control Board CVRWQCB, are published in the Water Quality Control Plan for the Sacramento and San Joaquin River Basins222, and define the resources, services, and qualities of aquatic systems that are the ultimate goals of protecting and achieving high water quality. The Sacramento and American rivers have been classified by the Central Valley Regional Water Quality Control Board (CVRWQCB) as having numerous beneficial uses, including providing municipal, agricultural, and recreational water supply. Other beneficial uses include freshwater habitat, spawning grounds, wildlife habitat, navigation on the Sacramento River, and industrial uses on the American River.22

In general, stormwater runoff within the City of Sacramento flows into either the City’s Combined Sewer System (CSS), which is treated at the County’s wastewater treatment plant or to the separated sewer system which conveys run-off to drainage system of pump stations which discharge run-off to the American, Sacramento Rivers and/or their respective tributaries The CSS is considered at or near capacity and requires all additional inflow into the system to be mitigated. Refer to section 4.11, Utilities and Service Systems, for more information on the City’s sewage and stormwater drainage facilities. Water quality requirements included in the Sacramento County Municipal Separate Storm Sewer System (MS4) permit are discussed under Regulatory Setting below.

4.7.2 Regulatory Setting

Federal

Surface Water Quality

Water quality objectives for all waters of the United States are established under applicable provisions of section 303 of the federal Clean Water Act (CWA). The CWA prohibits the discharge of pollutants to navigable waters from a point source unless authorized by a National Pollutant Discharge Elimination System (NPDES) permit. Because implementation of these regulations has been delegated to the State, additional information regarding this permit is discussed under the “State” subheading, below.

Standards for a total of 81 individual constituents have been established under the Safe Drinking Water Act, as amended in 1996. The U.S. Environmental Protection Agency (EPA) may add additional constituents in the future. Please see section 4.11, Utilities and Service Systems, for an analysis of effects related to potable water supply.

22 Central Valley Regional Water Quality Control Board, 2011. Water Quality Control Plan for the Sacramento and

San Joaquin River Basins. October 2011. pp. II-5.00-II-8.00.





National Pollutant Discharge Elimination System Permits

The NPDES permit system was established in the CWA to regulate municipal and industrial point discharges to surface waters of the U.S. Each NPDES permit for point discharges contains limits on allowable concentrations of pollutants contained in discharges. Sections 401 and 402 of the CWA contain general requirements regarding NPDES permits. Section 307 of the CWA describes the factors that the EPA must consider in setting effluent limits for priority pollutants.

The CWA was amended in 1987 to require NPDES permits for non-point source (i.e., stormwater) pollutants in discharges. Stormwater sources are diffuse and originate over a wide area rather than from a definable point. The goal of NPDES stormwater regulations is to improve the quality of stormwater discharged to receiving waters to the “maximum extent practicable” through the use of structural and non-structural Best Management Practices (BMPs). BMPs can include the development and implementation of various practices including educational measures (workshops informing public of what impacts results when household chemicals are dumped into storm drains), regulatory measures (local authority of drainage facility design), public policy measures, and structural measures (filter strips, grass swales and detention ponds). The NPDES permits that apply to activities in the City of Sacramento are described under local regulations below.

Floodplain Regulations

Federal regulations governing development in a floodplain are set forth in Title 44, Part 60 of the Code of Federal Regulations (CFR).23 FEMA imposes building regulations on development within flood hazard areas depending upon the potential for flooding within each area. Building regulations are incorporated into the municipal code of jurisdictions participating in the NFIP. Section 15.104, Floodplain Management Regulations, of the Sacramento City Code includes requirements for compliance with Title 44, Part 60 of the CFR. FEMA does not regulate buildings or require flood insurance in areas designated Zone X, such as the project site. Regulations do apply to structures and development in Zone AE and are outlined in Sacramento City Code Section 15.104.050, Requirements for flood hazard reduction. While the offsite digital billboard sites I-5 at San Juan Road and I-5 at Bayou Road are in Zone AE, the floodplain management regulations in Section 15.104.050 of the Sacramento City Code would not apply because digital billboards are not structures with two or more rigid walls and a roof.24

State

Surface Water Quality

The State Water Resources Control Board (SWRCB) and CVRWQCB are delegated authority from EPA to implement portions of the CWA, and the State’s water quality law, the Porter-Cologne Water Quality Control Act (Porter-Cologne Act). These agencies have established water quality standards that are required by section 303 of the CWA and the Porter-Cologne Act. The Porter-

23 Code of Federal Regulations, 2002. Title 44, Emergency Management and Assistance, Part 60, Criteria for Land

Management and Use. October 1, 2002. 24 Federal Emergency Management Agency. 2011. NFIP Manual, General Rules. October 1, 2011. p. GR-3.





Cologne Act states that basin plans will consist of beneficial uses, water quality objectives, and a program of implementation for achieving water quality objectives. A Water Quality Control Plan, or Basin Plan, prepared by the CVRWQCB, establishes water quality numerical and narrative standards and objectives for rivers and their tributaries within the area subject to the Basin Plan. In cases where the Basin Plan does not contain a standard for a particular pollutant, other criteria apply such as EPA water quality criteria developed under section 304(a) of the CWA.

Water quality objectives for the Sacramento River are specified in the Water Quality Control Plan for the Sacramento River Basin and San Joaquin River Basin (Basin Plan) prepared by the CVRWQCB in compliance with the federal CWA and the California Water Code (section 13240). The Basin Plan establishes water quality objectives and implementation programs to meet stated objectives and to protect the beneficial uses of water in the Sacramento-San Joaquin River Basin. Because the City of Sacramento and the project site are located within the Sacramento River Basin, all discharges to surface water or groundwater fall under the CVRWQCB’s jurisdiction and are subject to the Basin Plan requirements. The requirements outlined in the NPDES permits that regulate development within the City are based on the Basin Plan requirements.

Construction Dewatering

Where groundwater levels tend to be shallow, dewatering during construction is sometimes necessary to keep trenches or excavations free of standing water when improvements or foundations/footings are installed. Clean or relatively pollutant-free water that poses little or no risk to water quality may be discharged directly to surface water under certain conditions. The CVRWQCB has adopted a general NPDES permit for short-term discharges of small volumes of wastewater from certain construction-related activities (General Dewatering Permit). Permit conditions for the discharge of these types of wastewaters to surface waters are specified in “General Order for Dewatering and Other Low-Threat Discharges to Surface Waters” (Order No. 5-00-175, NPDES No. CAG995001). Discharges may be covered by the General Dewatering Permit provided they are (1) either four months or less in duration or (2) the average dry weather discharge does not exceed 0.25 million gallons per day. Construction dewatering, well development water, pump/well testing, and miscellaneous dewatering/low-threat discharges are among the types of discharges that may be covered by the General Dewatering Permit. The General Dewatering Permit also specifies standards for testing, monitoring, and reporting, receiving water limitations, and discharge prohibitions. When project construction would exceed four months in duration or 0.25 million gallons per day, a project-specific permit from the CVRWQCB is required. Construction activities at the project site would include dewatering of 1 million gallons per day for up to 15 months. Therefore, a project-specific permit would be required. Impacts associated with construction dewatering and the South Plume are addressed entirely within section 4.6, Hazards and Hazardous Materials.

Construction Site Runoff Management

In accordance with NPDES regulations, to minimize the potential effects of construction runoff on receiving water quality, the state requires that any construction activity affecting one acre or more obtain coverage under a General Construction Activity Stormwater Permit (General Construction Permit). The current General Construction Permit is the NPDES General Permit for





Storm Water Discharges Associated with Construction and Land Disturbance Activities, Order No. 2009-0009-DWQ, NPDES No. CAS000002, effective July 1, 2010. General Construction Permit applicants are required to prepare and implement a Stormwater Pollution Prevention Plan (SWPPP) which includes implementing BMPs to reduce construction effects on receiving water quality by implementing erosion and sediment control measures and reducing or eliminating non-stormwater discharges. Examples of typical construction BMPs included in SWPPPs include, but are not limited to: using temporary mulching, seeding, or other suitable stabilization measures to protect uncovered soils; storing materials and equipment so as to ensure that spills or leaks cannot enter the storm drain system or surface water; developing and implementing a spill prevention and cleanup plan; and installing sediment control devices such as gravel bags, inlet filters, fiber rolls, or silt fences to reduce or eliminate sediment and other pollutants from discharging to the City drainage system or receiving waters.

Construction activity that results in soil disturbances of less than one acre is subject to the General Construction Permit if there is potential for significant water quality impairment resulting from the activity as determined by the Regional Water Quality Control Board (RWQCB). The City review process in terms of construction management and water quality for projects on sites less than one acre mirrors the process for sites larger than one acre. The City of Sacramento requires an erosion and sediment control plan and standard construction BMPs for other pollutants are required for construction sites less than one acre.

Central Valley Flood Management

The Central Valley Flood Management Planning (CVFMP) Program was launched by DWR in 2008 to guide, manage, and implement integrated flood management actions for the Sacramento and San Joaquin valleys as required by Senate Bill 5, which was passed in 2007 (California Water Code Sections 9600 to 9651). Currently, the CVFMP is supporting the planning and coordination of major implementation actions of the 2012 Central Valley Flood Protection Plan (CVFPP), including State-led Basin-wide Feasibility Studies (BWFS), locally-led Regional Flood Management Planning, and the Central Valley Flood System Conservation Strategy. Each of these planning efforts will be incorporated into the next update of the CVFPP, which is scheduled for 2017. Implementation of CVFPP actions have already begun and will be expanded after the 2017 Plan is updated. The Downtown project site is located within the Lower Sacramento North / Delta North Regional Flood Management Planning region. The preparation of the Regional Flood Management Plan for the Sacramento North / Delta North is currently underway. As a part of the process, projects that would improve flood control within the region will be identified and ranked.25 In addition, the passage of Senate Bill 5 effectively set a higher flood protection threshold for urban areas by requiring a minimum of 200-year protection by 2025.26 The City must have a plan in place to achieve 200-year protection by July 2016.

25 California Department of Water Resources, 2013b. Central Valley Flood Management (CVFMP) Program.

http://www.water.ca.gov/cvfmp/. Accessed September 13, 2013. 26 California Water Code. Central Valley Flood Protection, Section 9600 – 9651.





Local

City of Sacramento 2030 General Plan

The following goals and policies from the 2030 General Plan are relevant to hydrology and water quality.

Goal U 4.1 Adequate Stormwater Drainage. Provide adequate stormwater drainage facilities and services that are environmentally sensitive, accommodate growth, and protect residents and property.

Policies

U 4.1.1 Adequate Drainage Facilities. The City shall ensure that all new drainage facilities are adequately sized and constructed to accommodate stormwater runoff in urbanized areas.

U 4.1.4 Watershed Drainage Plans. The City shall require developers to prepare watershed drainage plans for proposed developments that define needed drainage improvements per City standards, estimate construction costs for these improvements, and comply with the City’s National Pollutant Discharge Elimination System (NPDES) permit.

U 4.1.5 New Development. The City shall require proponents of new development to submit drainage studies that adhere to City stormwater design requirements and incorporate measures to prevent on-or off-site flooding.

Goal ER 1.1 Water Quality Protection. Protect local watersheds, water bodies and groundwater resources, including creeks, reservoirs, the Sacramento and American rivers, and their shorelines.

Policies

ER 1.1.3 Stormwater Quality. The City shall control sources of pollutants and improve and maintain urban runoff water quality through storm water protection measures consistent with the City’s National Pollutant Discharge Elimination System (NPDES) Permit.

ER 1.1.4 New Development. The City shall require new development to protect the quality of water bodies and natural drainage systems through site design, source controls, storm water treatment, runoff reduction measures, best management practices (BMPs), Low Impact Development (LID), and hydromodification strategies consistent with the City’s NPDES Permit.

ER 1.1.5 No Net Increase. The City shall require all new development to contribute no net increase in stormwater runoff peak flows over existing conditions associated with a 100-year storm event.





ER 1.1.6 Post-Development Runoff. The City shall impose requirements to control the volume, frequency, duration, and peak flow rates and velocities of runoff from development projects to prevent or reduce downstream erosion and protect stream habitat.

ER 1.1.7 Construction Site Impacts. The City shall minimize disturbances of natural water bodies and natural drainage systems caused by development, implement measures to protect areas from erosion and sediment loss, and continue to require construction contractors to comply with the City’s erosion and sediment control ordinance and stormwater management and discharge control ordinance.

Goal EC 2.1 Flood Protection. Protect life and property from flooding.

Policies

EC 2.1.6 New Development. The City shall require evaluation of potential flood hazards prior to approval of development projects.

The Proposed Project would be consistent with each of the 2030 General Plan goals and policies listed above. Consistent with Policy U 4.1.1 and as discussed below under Impact 4.7-2, project stormwater drainage infrastructure would be appropriately sized to accommodate runoff from the project site. Consistent with policies U 4.1.4 and U 4.1.5, the project applicant would submit a watershed drainage plan and drainage studies to the City for review and approval. As discussed under Impact 4.7-1 below, the project is subject to the City’s NPDES permit and, therefore, would comply with policies ER 1.1.3 or ER 1.1.4. A SWPPP would be required, which would ensure consistency with Policy ER 1.1.7. The project would be designed to be consistent with policies ER 1.1.5 and ER 1.1.6 so that no net increase in 100-year peak stormwater flows would occur and all City requirements regarding the volume, frequency, duration, and peak flow rates and velocities of runoff would be met (see the discussion under Impact 4.7-2 below). An evaluation of potential flood hazards as a result of the Proposed Project is included below under section 4.7.3, Analysis, Impacts, and Mitigation, so the project would be consistent with Policy EC 2.1.6.

Stormwater Quality/Urban Runoff Management

The County of Sacramento and the cities of Sacramento, Folsom, Citrus Heights, Elk Grove, Rancho Cordova, and Galt have a joint Municipal Separate Storm Sewer System NPDES permit (MS4 Permit) (No. CAS082597) that was granted on September 11, 2008. Collectively, these jurisdictions are referred to as the Sacramento Stormwater Quality Partnership (Partnership). The MS4 Permit is intended to implement the Basin Plan through the effective implementation of BMPs to reduce pollutants in stormwater discharges to the maximum extent practicable. The permittees listed under the joint permit have the authority to develop, administer, implement, and enforce storm water management programs within their own jurisdiction.

Urban storm water runoff is defined in the MS4 Permit as including stormwater and dry weather flows from a drainage area that reaches a receiving water body or subsurface. The permit regulates the discharge of all wet and dry weather urban storm water runoff within the City of





Sacramento and requires the City to implement a stormwater management program to reduce pollutants in stormwater to the maximum extent practicable. In response, the City of Sacramento and the other Permittees created the Stormwater Quality Improvement Plan (SQIP) to address the MS4 permit requirements and reduce the pollution carried by stormwater into local creeks and rivers. The program includes pollution reduction activities for construction sites, industrial sites, illegal discharges and illicit connections, new development, and municipal operations. The program also includes an extensive public education effort, target pollutant reduction strategy and monitoring program. The SQIP also outlines the priorities, key elements, strategies, and evaluation methods of the program.27

The specific BMPs that are appropriate for a project to meet the requirement of reducing the discharge of pollutants to the maximum extent practicable are site specific. During the design process, the appropriate required measures and Low Impact Development (LID)28 strategies are selected and incorporated into project plans. The County of Sacramento and the cities of Sacramento, Folsom, Citrus Heights, Elk Grove, Rancho Cordova, Galt, and Roseville collaboratively published the Stormwater Quality Design Manual for Sacramento and South Placer Regions (May 2007) to meet MS4 Permit requirements and to provide clear guidance for project applicants on how to incorporate BMPs that achieve permit compliance.29 The manual provides locally-adapted information for design and selection of three categories of stormwater quality control measures: source control, runoff reduction, and treatment control. The second edition of the Stormwater Quality Design Manual is expected to be available by the end of 2014 and will include LID standards. The following are required items for each of the local permitting agencies as specified in the new development element provisions of the MS4 permit:

the types of projects subject to the development standards and thresholds for determining what types of control measures apply to the project;

maintenance agreements or covenants are required for selected control measures; and

sizing methodology for water quality flow (WQF) -based measures (e.g., vegetated swale) and water quality volume WQV-based measures (e.g., water quality detention basin).

The Sacramento Stormwater Quality Partnership Hydromodification Management Plan (HMP) was released in July 2011 to provide an additional resource for stormwater management strategies. The HMP was subsequently revised in February 2013 to address CVRWQCB comments and is anticipated to be approved in early 2014. The HMP includes hydromodification management exemption criteria that apply to this project, but has not been approved by the CVRWQCB yet. The Partnership is also currently working on the development of LID standards,

27 County of Sacramento and the Cities of Sacramento, Citrus Heights, Elk Grove, Folsom, Galt, and Rancho

Cordova, 2009. Stormwater Quality Improvement Plan. April 2009. pp. 1-1–1-16. 28 Low Impact Development uses site design and stormwater management to maintain pre-development runoff rates

and volumes through the use of decentralized design techniques that infiltrate, filter, store, evaporate, and detain runoff.

29 Cities of Citrus Heights, Elk Grove, Folsom, Galt, Rancho Cordova, Roseville, Sacramento and the Sacramento County. Stormwater Quality Design Manual for the Sacramento and South Placer Regions. pp. 1-1 - 1-8.





which will be incorporated in the second edition of the Stormwater Quality Design Manual and take effect a year after the HMP is approved by the CVRWQCB.

Dewatering

All groundwater discharges to the CSS or separated sewer system are regulated by the City of Sacramento Department of Utilities pursuant to Department of Utilities Engineering Services Policy No. 0001, adopted as Resolution No. 92-439 by the Sacramento City Council. Groundwater discharges to the City's sewer system are defined as construction dewatering discharges, foundation or basement dewatering discharges, treated or untreated contaminated groundwater cleanup, discharges, and uncontaminated groundwater discharges.

Project construction would include dewatering at the Downtown project site. In addition to the State requirements described above, the City requires that any short-term discharge be permitted, or an approved Memorandum of Understanding (MOU) for long-term discharges be established, between the discharger and the City. Short-term limited discharges of seven days or less must be approved through the City Department of Utilities by an approval letter. Long-term discharges of greater than seven days must be approved through the City Department of Utilities and the Director of the Department of Utilities through an MOU process. The MOU must specify the type of groundwater discharge, flow rates, discharge system design, a City-approved contaminant assessment of the proposed groundwater discharge indicating tested levels of constituents, and a City-approved effluent monitoring plan to ensure contaminant levels remain in compliance with state standards or Sacramento Regional County Sanitation District (SRCSD)- and CVRWQCB-approved levels. All groundwater discharges to the sewer must be granted an SRCSD discharge permit. If the discharge is part of a groundwater cleanup or contains excessive contaminants, CVRWQCB or Sacramento County approval is also required. Impacts associated with construction dewatering and the South Plume are addressed within section 4.6, Hazards and Hazardous Materials.

Combined Sewer System Discharges

Section 13.080.030 of the Sacramento City Code prohibits the discharge of any substances, materials, waters, or waste if the discharge would violate any sewer use ordinance enacted by the SRCSD. Section 13.08.040 of the Sacramento City Code identifies specific waters, wastes, and substances that may not be discharged to the sewer.

Discharges to the CSS are regulated under a separate NPDES permit (NPDES No. CA007911). Any discharger into the CSS must have a completed Sewer Use Questionnaire on file with the SRCSD, which would apply to the Downtown project site. The SRCSD has adopted a Sewer Use Ordinance that regulates the use of public sewers connected to the Sacramento Regional Wastewater Treatment Plant (SRWTP). The wastewater discharged from the SRWTP to the Sacramento River is regulated under another NPDES permit issued by the CVRWQCB (NPDES No. CA0077682). Discharge limitations are specified in the permit to limit water quality impacts in the Sacramento River. Categorical Pretreatment Standards have also been established for the pretreatment of certain classes of industrial wastes discharged to publicly owned treatment works, such as the SRWTP. The purpose of these standards is to protect the SRWTP and the





environment by regulating potentially harmful discharges to the sewer from industrial and commercial businesses.

City of Sacramento Construction Site Stormwater Controls

The City's Grading, Erosion and Sediment Control Ordinance requires project applicants to prepare erosion, sediment and pollution control plans for both during and after construction of a project, and grading plans. The Ordinance applies to projects where 50 cubic yards or more of soil is excavated and/or disposed and requires BMPs that must be approved of by the City's Department of Utilities. In addition, the City’s Stormwater Management and Discharge Control Ordinance minimizes or eliminates sediment and pollutants in construction site stormwater discharges.

4.7.3 Analysis, Impacts, and Mitigation

Significance Criteria

The Proposed Project would result in a significant effect if it would:

(1) substantially degrade water quality;

(2) violate any water quality or waste discharge objectives set by the State Water Resources Control Board, due to increases in sediments and other contaminants generated by construction and/or development of the project;

(3) substantially increase the exposure of people and/or property to the risk of loss, injury, damage, or death in the event of a 100-year flood or as a result of the failure of a levee or dam;

(4) create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems or provide substantial additional sources of polluted runoff;

(5) place within a 100-year flood hazard area structures which would impede or redirect flood flows;

(6) substantially deplete groundwater supplies or interfere with groundwater recharge resulting in a net deficit in the aquifer volume, a lowering of the groundwater table, or subsidence;

(7) substantially alter the existing site drainage or substantially increase the rate or amount of surface runoff which would result in flooding on or off-site.

The first portion of significance criterion (4), “create or contribute runoff water which would exceed the capacity of existing or planned stormwater drainage systems” is addressed in section 4.11, Utilities and Service Systems. The remainder of significance criterion (4) is addressed below. With regard to significance criterion (5), the project site is not located within a 100-year flood hazard area as described above under section 4.7.1, Environmental Setting. Therefore, significance criterion (5) does not apply to the Proposed Project, and no further analysis is required.





Methodology and Assumptions

The following impact analyses are qualitative and based on existing hydrologic and water quality information. It is assumed that all aspects of the Proposed Project would comply with all applicable laws, regulations, design standards, and plans. Impacts on water quality were evaluated by considering the type of pollutants the project would generate during construction and operation and whether meeting the requirements of applicable regulations would reduce potential impacts to a less-than-significant level. Onsite drainage impacts were evaluated in the same manner as water quality impacts. Potential impacts related to flooding were analyzed by comparing the 100-year floodplain boundary as defined by FEMA with the location of the project site. The analysis of impacts to groundwater considers how redevelopment of the Downtown project sites and installation of offsite digital billboards at the 10 potential locations would influence groundwater recharge based on increases in impervious surfaces as a result of the project and the existing and projected condition of the groundwater basin. An analysis of impacts to water supply, sewer, and stormwater infrastructure is included in section 4.11, Utilities and Service Systems. Impacts associated with the South Plume are addressed entirely within section 4.6, Hazards and Hazardous Materials.

Impacts and Mitigation Measures

Impact 4.7-1: The Proposed Project could degrade water quality.

Downtown Project Site

Construction

The use of construction equipment and other vehicles could result in spills of oil, grease, gasoline, brake fluid, antifreeze, or other vehicle-related fluids and pollutants. Improper handling, storage, or disposal of fuels and materials or improper cleaning of machinery could result in accidental spills or discharges that could degrade water quality. Regarding construction dewatering, sediment impairment of receiving waters could result if dewatering discharge is sediment laden. The effects of construction dewatering and the South Plume are addressed in section 4.6, Hazards and Hazardous Materials.

As discussed in the Regulatory Setting, above, the Proposed Project is required to comply with a number of regulations designed to reduce or eliminate construction-related water quality effects, including the NPDES General Construction Permit; SQIP; Grading, Erosion and Sediment Control Ordinance; and project-specific dewatering discharge permit. Before the onset of any construction activities, an application for coverage under the General Construction Permit and an erosion and sediment control plan must be submitted to the City. Before construction may begin, a SWPPP would be developed and a Notice of Intent (NOI) filed with the CVRWQCB. After approvals of coverage under the General Construction Permit, the erosion and sediment control plan, and the SWPPP are obtained, construction would commence and include all BMPs outlined in the erosion and sediment control plan and SWPPP. BMPs may consist of a wide variety of measures taken to reduce pollutants in stormwater and other non-point source runoff. The City would complete inspections to verify that the erosion and sediment control plan and SWPPP are implemented correctly.





The City would also require erosion and sediment control plans to include BMPs to minimize the potential for, and effects from, spills of hazardous, toxic, or petroleum substances during construction activities for all contractors. Implementation of these measures would comply with state and federal water quality regulations. The federal reportable spill quantity for petroleum products, as defined in 40 CFR 110, is any oil spill that:

violates applicable water quality standards;

causes a film or sheen on, or discoloration of, the water surface or adjoining shoreline; or

causes a sludge or emulsion to be deposited beneath the surface of the water or adjoining shorelines.

If a spill occurs, the contractor’s superintendent would notify the City, and the contractor would take action to contact the appropriate safety and clean-up crews to ensure that a Spill Prevention and Control Program (SPCP) is followed. In addition, the City would respond and investigate any spills reported. A written description of reportable releases would be submitted to the CVRWQCB and the Department of Toxic Substances Control (DTSC) by the contractor or land owner. If an appreciable spill occurs and results determine that construction activities have adversely affected surface water or groundwater quality, a detailed analysis would be performed to the specifications of DTSC to identify the likely cause of contamination. This analysis would include recommendations for reducing or eliminating the source or mechanisms of contamination. Based on this analysis, contractors would select and implement measures to control contamination, with a performance standard that surface and/or groundwater quality must be returned to baseline conditions. These measures would be subject to approval by the City and/or the CVRWQCB.

Prior to discharge of dewatered effluent, the contractor would be required to obtain a project-specific permit from the CVRWQCB that includes specific requirements and establishes discharge limits. A project-specific permit is required because the Downtown project site is located above a portion of the South Plume. Impacts associated with construction dewatering and the South Plume are addressed entirely within section 4.6, Hazards and Hazardous Materials.

In light of the existing developed conditions, compliance with the SQIP, Land Grading and Erosion Control Ordinance, NPDES General Construction Permit, and project-specific dewatering permit would prevent the substantial degradation of water quality during project construction. These regulatory instruments are designed to ensure that construction projects result in water quality discharges that are not in violation of SWRCB objectives. This impact would be less than significant.

Operation

During operation, runoff from the project site would contain pollutants common in urban runoff including metals; oils and grease; pesticides; herbicides; nutrients; pet waste; and garbage/litter. Without BMPs to remove these pollutants, stormwater leaving the Downtown project site could degrade the quality of receiving waters. The City of Sacramento currently implements the SQIP, which is designed to reduce stormwater pollution to the maximum extent practicable and eliminate prohibited non-stormwater discharges through a NPDES municipal stormwater





discharge permit. The City of Sacramento also provides direction on post-construction BMPs in the Stormwater Quality Design Manual for the Sacramento and South Placer Regions. The Proposed Project would be subject to City of Sacramento General Plan policies U 4.1.4, ER 1.1.3, ER 1.1.4, and ER 1.1.7; the City’s ordinances; the SQIP; the Stormwater Quality Design Manual for Sacramento and South Placer Regions; and the MS4 Permit and NPDES permit for the CSS, and would meet the state water quality discharge criteria. Specifically, the project would be required to comply with the following permits and plans:

Sacramento-area Phase I NPDES Municipal Separate Storm Sewer System Permit (No. CAS082597);

NPDES Permit for City of Sacramento Combined Wastewater Collection and Treatment System Sacramento County (No. CA0079111);

Stormwater Quality Design Manual for the Sacramento and South Placer Regions (Design Manual) BMPs, and LID measures to reduce pollutants in storm water and nonstormwater discharges to the Maximum Extent Practicable;

City of Sacramento Stormwater Management and Discharge Control Code; and

City of Sacramento General Plan policies related to hydrology and water quality, and the protection and preservation of natural resources.

Permanent onsite water quality treatment meeting the requirements specified in the Stormwater Quality Design Manual for the Sacramento and South Placer Regions will be required for any surface drainage from the project that flows to the City’s separated drainage system. The Proposed Project would also be designed to comply with the regulatory requirements listed above and to obtain certification under the United States Green Building Council (USGBC) Leadership in Energy and Environmental Design (LEED) program. Specific BMPs have not been identified because project design is in an early phase. The project development process includes identification of BMPs that respond to the design and construction methods of the project. The BMPs are implemented to ensure that water quality would not be degraded and the violation of water quality or waste discharge objectives set by the SWRCB would not occur. City review would confirm that BMP implementation complies with all applicable regulations. The LEED certification process also requires extensive coordination with the USGBC, and through that coordination, identifies measures that ensure that water pollutant removal would be implemented in full compliance with the program and certification requirements. Given that regulations are in place to ensure that the project would not result in an impact to water quality, this impact would be less than significant.

Operational dewatering currently occurs at the Downtown project site and the pumped groundwater is discharged to the CSS. Metals, diesel- and oil-range organics (DROs and OROs), and Volatile Organic Compounds (VOCs) were detected in groundwater samples taken below the Downtown project site in October 2013 (see Appendix I). Antimony, arsenic, barium, chromium, copper, molybdenum, vanadium and zinc were detected in the samples, and antimony, arsenic, and vanadium were detected at concentrations that exceed the Environmental Screening Levels (ESLs) and Maximum Contaminant Levels (MCLs). At three sampling locations, DROs were





detected at concentrations exceeding the ESL for drinking water. Four samples contained OROs at concentrations greater than the ESL for drinking water. The VOC vinyl chloride was also detected at levels higher than the ESL and MCL. The Proposed Project would incrementally eliminate the seasonal dewatering system by constructing buildings with waterproof foundations. As the project is implemented and groundwater dewatering is phased out at the Downtown project site, water quality in the CSS may improve given the constituents found during recent groundwater monitoring. Therefore, this impact would be less than significant. An analysis of the capacity of the CSS to convey pumped groundwater from the site during project operation is included in section 4.11, Utilities and Service Systems.

Offsite Digital Billboards

The offsite digital billboard sites are each less than one acre in size. Sites that are less than one acre are required to submit an erosion and sediment control plan to the City for approval prior to the commencement of installation activities. Standard construction BMPs would also need to be outlined by the applicant for City review and approval prior to billboard installation. Additional requirements, including a formal wetland delineation for review and approval by the USACE, would apply to the SR 99 at Calvine Road site because of its proximity to wetlands and to the I-5 at San Juan Road site because of its proximity to a drainage basin. Those requirements are addressed in section 4.3, Biological Resources. As with the project components at the Downtown project site, regulatory compliance would prevent the substantial degradation of water quality during project construction. During operation, the offsite digital billboards would not represent a new source of polluted runoff and, therefore, would not substantially degrade water quality. This impact would be less than significant.

Mitigation Measure

None required.

Impact 4.7-2: Implementation of the Proposed Project could increase the risk of flooding on- or off-site.


Construction

The project site is located within FEMA Flood Zone X, which applies to areas of minimal flood hazard outside of the 100-year flood hazard zone. Generally, the southern half of the site is within the 500-year floodplain but protected from the 500-year flood by a levee, and the remainder of the site is outside of the 500-year floodplain. The project would, therefore, not expose people or property to the risk of loss, injury, damage, or death in the event of the 100-year flood nor would it place structures that could impede or redirect flood flows within the 100-year floodplain during construction. This impact would be less than significant.





Pursuant to the requirements of state law, in the future, flood protection in downtown Sacramento will be increased to a minimum of 200-year protection (exposure to no greater than the 0.5 percent flood). In acknowledgement of that requirement, this analysis also considers effects related to the 200-year flood. As described above, 200-year floodplain maps have not yet been finalized for the Sacramento area. While not expected, it is possible that when maps are developed they will indicate that a part of the southern portion of the project site is in the 200-year floodplain. The northern portion of the Downtown project site is located outside of the 500-year floodplain and, therefore, would not be within the 200-year floodplain. While it is possible that people and property could be exposed to the 200-year flood during project construction in the southern portion of the site, it is not anticipated given the location of the 100- and 500-year floodplain boundaries.

Regarding the alteration of site draining that could result in on- or off-site flooding, BMPs implemented in compliance with the SQIP, Land Grading and Erosion Control Ordinance, and NPDES General Permits must also control the rate or amount of surface runoff from the project site such that flooding on or off-site would not occur. Additionally, construction of the project would not involve activities that would affect levee maintenance or regional flood management planning, nor would ongoing flood planning and maintenance efforts conflict with the construction of the Proposed Project. This impact would be less than significant.

Operation

As described above, the project site is located within FEMA Flood Zone X, which applies to areas of minimal flood hazard outside of the 100-year flood hazard zone. During operation, the project would, therefore, not expose people or property to the risk of loss, injury, damage, or death in the event of the 100-year flood nor would it place structures that could impede or redirect flood flows within the 100-year floodplain during construction. This impact would be less than significant.

The project site and vicinity are fully developed with intense residential and non-residential uses. The Proposed Project would introduce residential uses to the site and increase the intensity of non-residential uses, and would, therefore, increase the number of people and value of property at the project site. Proposed residential uses would be located within the northern portion of the project site, and would, therefore, not be exposed to the 200-year flood. Proposed uses within the southern portion of the site that could potentially be exposed to the 200-year flood include the southern arena structure and the player parking lot below the practice facility. Given that it is uncertain whether any portion of the project site is in the 200-year floodplain boundary; that by law, 200-year protection will be provided in the future; and that the uses that are potentially at risk are parking and the event level of the arena structure, which are non-residential, this impact is considered less than significant.

The project site is currently impervious with the exception of a half-acre area at the southeast corner of 4th and J streets. After project implementation, the site would become completely impervious. The half-acre increase in impervious area that would result from project implementation would not cause substantial alteration of onsite drainage, particularly because the parcel at the southeast corner of 4th and J streets slopes toward a connection with the storm drain





system and minimal percolation currently occurs. In terms of potential for onsite flooding, the onsite drainage system would be designed to comply with all City design requirements, General Plan Policies ER 1.1.4 and ER 1.1.5, and NPDES permit requirements such that onsite flooding would not occur.

As discussed in section 4.11, Utilities and Service Systems, the CSS and Storm Drainage Basin 52 flood during storms due to insufficient capacity. If the Proposed Project resulted in a greater volume of stormwater than is currently discharged to the CSS and Storm Drainage Basin 52 systems during a storm, the impact to these systems would be considered significant. Several BMPs and other stormwater management strategies exist that would prevent such impacts. The project would incorporate LID measures, and the project applicant would coordinate with City staff on designing the measures to be consistent with the LID standards that the City is currently developing. However, the potential for any increase in flows to the CSS and Basin 52 is significant.


As shown in Table 4.7-3, offsite digital billboard locations 1 through 7 and 10 are either outside of any flood hazard zone or mapped within Zone X. The two proposed billboard sites in Natomas, I-5 at Bayou Road and I-5 at San Juan Road, are located within Zone AE, which is the zone that applies to the 100-year floodplain (area with a 1 percent chance of flooding in a given year). None of the offsite digital billboard sites are located within a designated floodway.

The placement of signs at locations 1 through 7 and 10 would not substantially increase the exposure of people and/or property to flood risk during installation or operation because they are would be located outside of areas of high flood hazard potential.

If a 100-year flood event were to occur during the installation of offsite digital billboards at either of the locations in Natomas, the crew and equipment would be at a higher flood risk; however, because installation would occur over five days, this would not be considered a substantial increase in the exposure of people and/or property to the risk of flooding. During operation and in the event of a 100-year flood, the sign posts within Zone AE would minimally affect overland water flow, but this would be very localized at the base of the 3-foot-wide sign post and would not substantially increase the exposure of offsite people and/or property to flood risk. The offsite digital billboards within Zone AE would themselves be at risk of damage due to flooding. Installation and operation of the proposed offsite digital billboards would not involve activities that would affect levee maintenance or regional flood management planning, nor would ongoing flood planning and maintenance efforts conflict with installation or operation of the proposed signs. This impact would be less than significant.

Mitigation Measure

The following mitigation measure is included in section 4.11, Utilities and Service Systems, of this EIR. Mitigation Measure 4.11-5 applies to wastewater, stormwater drainage, and dewatered groundwater. The actions related to stormwater drainage are applicable to the impacts associated with increases in discharge to the CSS and Basin 52.





4.7-2 (ESC/PUD)

Implement Mitigation Measure 4.11-5.

Mitigation Measure 4.11-5 requires that the project applicant manage wastewater, drainage and dewatered groundwater from the Proposed Project such that they do not exceed existing CSS and Basin 52 system capacity.

Impact Significance After Mitigation: With implementation of Mitigation Measure 4.11-5, the onsite drainage system would be designed so that during storm events, impacts to the CSS and Storm Drainage Basin 52 would be avoided. Therefore, with implementation of Mitigation Measure 4.7-2, this impact would be less than significant.

Impact 4.7-3: The Proposed Project could substantially deplete groundwater supplies.


Construction

Project construction would involve dewatering of approximately 1 million gallons per day for up to 15 months for a maximum volume of 450 million gallons or 1,381 acre-feet. Dewatering activities would be temporary and take place in an area that is hydraulically connected to the Sacramento River. The groundwater withdrawn during dewatering would be very small relative to the calculated groundwater storage capacity of the South American Subbasin (4,816,000 acre-feet). A volume of 1,381 acre-feet is not sufficient to substantially deplete groundwater supplies in the basin. Groundwater recharge does not occur currently at the project site with the exception of the half-acre area at the southeast corner of 4th and J streets where very minimal infiltration occurs due to site slope. Therefore, project demolition, excavation, construction, and landscaping would not interfere with groundwater recharge.

One potential effect of dewatering is subsidence, which can result when groundwater is removed from the aquifer to the extent that the aquifer collapses and overlying land subsides. Subsidence can also result in ground collapse, and building foundations can be damaged or fail. The potential for subsidence depends in part on the soil profile. The Proposed Project includes a dewatering monitoring program that would avoid any potential subsidence. The program would include soil borings prior to construction, which would identify any areas susceptible to subsidence during dewatering. The Proposed Project would also install a system of wells in areas up to three-quarters of a mile around the Downtown project site prior to construction to develop historical data that would be used to identify subsidence parameters. For specific areas, such as the loading dock on the 5th Street side of event level, and also along the Hotel Marshall parcel on 7th Street, “shallow well point” systems would be used to reduce the “cone of influence” that typically occurs with dewatering systems of any type. Groundwater levels would continue to be monitored during construction, and dewatering rates would be adjusted to meet the subsidence parameters.





Because the Proposed Project would not directly withdraw groundwater for potable water supply, would not increase impervious surface over the aquifer, and would monitor and adjust dewatering rates to prevent subsidence, this impact would be less than significant.

Operation

The Proposed Project would not directly withdraw groundwater during operation for water supply because water would be supplied from the City’s system. Please see section 4.11, Utilities and Service Systems, for a discussion of project impacts related to water supply, including groundwater.

The Downtown project site is located within Downtown Sacramento, which is not an important groundwater recharge area due to the extent of impervious surfaces. The Downtown project site is currently impervious with the exception of a half-acre area at the southeast corner of 4th and J streets. After project implementation, the project site would become completely impervious; and the project would result in a very small decrease in the amount of water that percolates to underlying aquifers. This decrease would not be of a sufficient magnitude to result in a net deficit in the aquifer volume or lowering of the groundwater table. Furthermore, current seasonal dewatering at the Downtown project site would be phased out as the Proposed Project builds out, reducing the amount of groundwater that is removed from the aquifer due to dewatering. For these reasons, this impact would be less than significant.


Temporary pumping of groundwater could be required during drilling of foundation holes up to 32-foot-deep for one or more of the offsite digital billboards. If groundwater pumping is deemed necessary at any of the offsite digital billboard locations, it would occur for no more than 24 hours. The amount of groundwater that would be removed during this period would not be of a sufficient volume to result in a net deficit in the aquifer volume or lowering of the groundwater table. Some of the proposed offsite digital billboards would be anchored in place with a 576 square-foot impervious concrete pad instead of a sign post that extends underground. Given the small area that the pads would cover, the introduction of these concrete pads would not interfere with groundwater recharge such that a net deficit in the aquifer volume of lowering of the groundwater table would result. This impact would be less than significant.

Mitigation Measure

None required.

Cumulative Impacts

Project effects on water quality and hydrology must be considered in light of other past, present, and future projects that could add to the effects of the project, creating cumulative effects. These effects may be contributed to by development within the Sacramento River watershed, which extends well beyond the City of Sacramento limits. The cumulative context for water quality considers the geographic scope of the Basin Plan and, therefore, development within the larger





Sacramento River watershed and the Sacramento–San Joaquin Delta (Delta). The Sacramento River watershed covers 27,000 square miles. The Delta extends for 24 miles from east to west and 48 miles from north to south where the Sacramento and San Joaquin rivers meet before discharging into the San Francisco Bay. The cumulative context for flooding impacts is also the Sacramento River watershed and Delta. With respect to groundwater, the cumulative context is the Central Sacramento County Groundwater Basin and North American Subbasin of the Sacramento Valley Groundwater Basin. Because impacts to stormwater infrastructure are more local in nature, the cumulative setting for impacts to stormwater conveyance is the City of Sacramento.

Impact 4.7-4: The Proposed Project could contribute to the cumulative degradation of water quality.

Non-point source water pollution from the combination of past, present, and future projects in the Sacramento River watershed and Delta, including residential, commercial, and industrial land development; agriculture; parks; transit; infrastructure; and other land uses could result in the degradation of water quality in the Sacramento River watershed and Delta. Cumulative land development in the City of Sacramento, in addition to other development in the Sacramento River watershed and Delta, would result in an increase in impervious surfaces and potentially an increase in urban runoff and water pollutants, if not properly mitigated. For example, as outlined in the Sacramento 2030 General Plan Master Environmental Impact Report (MEIR), planned development in the Greenbriar, Panhandle, Camino Norte, and Delta Shores specific plans alone would result in an additional 2,256 acres of impervious cover.30 In addition to these specific plans, there are many more potential development projects within the Sacramento River watershed and Delta that may contribute to increases in urban runoff volume and pollutants. Older land development that was constructed without BMPs to control the transport of water pollutants continues to represent a non-point source of polluted stormwater runoff. While agricultural runoff is regulated, it is a major non-point source of a variety of water pollutants. While new development is less likely to significantly degrade water quality because of existing regulations, older development, agriculture, and other non-point sources could impair receiving water quality. This is considered a significant cumulative impact.

The City of Sacramento currently implements the SQIP, which is designed to reduce stormwater pollution to the maximum extent practicable and eliminate prohibited non-stormwater discharges through a NPDES municipal stormwater discharge permit. The City of Sacramento also provides direction on post-construction BMPs in the Stormwater Quality Design Manual for the Sacramento and South Placer Regions. The Proposed Project would be subject to City of Sacramento General Plan Policies U 4.1.4, ER 1.1.3, ER 1.1.4, and ER 1.1.7; the City’s ordinances; the SQIP; the Stormwater Quality Design Manual for Sacramento and South Placer Regions; and the General Permit, General Dewatering Permit, MS4 Permit, and NPDES permit for the CSS, and would meet the state water quality discharge criteria. As discussed under Impact 4.7-1 above, through compliance with these permits and plans, the Proposed Project would reduce

30 City of Sacramento, 2009. Sacramento 2030 General Plan Master Environmental Impact Report (SCH No.

2007072024). Certified March 3, 2009. p. 6.7-30.





project generation of water pollutants to the maximum extent practicable consistent with the goal of NPDES stormwater regulations through the use of structural and non-structural BMPs as well as measures to meet the requirements for LEED certification. Therefore, the project’s contribution to the significant cumulative impact would not be considerable. This impact would be less than significant.

Mitigation Measure

None required.

Impact 4.7-5: The Proposed Project could contribute to cumulative increases in the risk of flooding.

Cumulative development within the City of Sacramento and other portions of the Sacramento River watershed and Delta could substantially increase the exposure of people and/or property to flood risk, particularly if development is located within a FEMA flood hazard zone or the 200-year floodplain. The population within the lower Sacramento watershed is expected to include an additional 1.36 million people in the next 30 years. Accommodating this growth in population would require an additional 306 square miles of development or an increase in density within existing urbanized areas of 40 percent.31 This growth would likely increase exposure to flood risk. This is considered a significant cumulative impact.

As described above, the project site is located within FEMA Flood Zone X, which applies to areas of minimal flood hazard outside of the 100-year flood hazard zone. During operation, the project would, therefore, not expose people or property to the risk of loss, injury, damage, or death in the event of the 100-year flood nor would it place structures that could impede or redirect flood flows within the 100-year floodplain during construction. Proposed uses within the southern portion of the project site that could potentially be exposed to the 200-year flood include the southern arena structure and the player parking lot below the practice facility. Given that it is uncertain whether any portion of the project site is in the 200-year floodplain boundary; that by law, 200-year protection will be provided in the future; and that the uses that are potentially at risk are parking and the event level of the arena structure, which is non-residential, the project’s contribution to the significant cumulative impact would not be considerable. This impact would be less than significant.

Two of the offsite digital billboard sites are located within the 100-year flood hazard zone, or FEMA Zone AE. Given the dimensions of the sign posts and concrete slabs (as applicable), a substantial increase in flood risk exposure would not occur offsite. Further, both the arena space and the offsite digital billboards could be used as emergency management resources in the event of severe flooding in the region. The project’s contribution to the significant cumulative impact would not be considerable. This impact would be less than significant. 31 City of Sacramento, 2009. Sacramento 2030 General Plan Master Environmental Impact Report (SCH No.

2007072024). Certified March 3, 2009. p. 6.7-35.





The project site is currently impervious with the exception of a half-acre area at the southeast corner of 4th and J streets. After project implementation, the site would become completely impervious. The half-acre increase in impervious area that would result from project implementation would not cause substantial alteration of site drainage, particularly because the parcel at the southeast corner of 4th and J streets slopes toward a connection with the storm drain system and minimal percolation currently occurs. As discussed under Impact 4.7-2 above, with implementation of Mitigation Measure 4.7-2, the onsite drainage system would be designed to comply with all City design requirements, General Plan Policies ER 1.1.4 and ER 1.1.5, and NPDES permit requirements such that runoff from the project site would not result in flooding due to capacity deficiencies in the CSS and Storm Drainage Basin 52 systems. The project’s contribution to the significant cumulative impact would be considerable. This is considered a significant impact.

Mitigation Measure

4.7-5 (ESC/PUD)

Implement Mitigation Measure 4.7-2.

Impact Significance After Mitigation: Implementation of Mitigation Measure 4.7-2 would ensure that the onsite drainage system could accommodate project flows so that they would not be considerable. With mitigation, the impact would be less than significant.

Impact 4.7-6: The Proposed Project could contribute to cumulative depletion of groundwater supplies.

The Central Sacramento County Groundwater Management Plan includes groundwater supply and demand projections through 2030. The comparison of supply and demand shows that supplies should be sufficient to meet demands through 2030. The plan acknowledges that there are more factors than just supply and demand that determine whether a groundwater basin is managed sustainably, and groundwater management objectives are identified in the plan.32 Because supply would be sufficient to meet demand and the groundwater basin would be managed sustainably so as to not exceed the calculated long-term average annual sustainable yield of 273,000 acre-feet per year, the Proposed Project would not increase use of groundwater beyond anticipated projections; therefore this cumulative impact would be less than significant.

Mitigation Measure

None required.

32 Water Forum, Sacramento County Water Agency, and MWH, 2006. Central Sacramento County Groundwater

Management Plan. February 2006. pp. 2-22 – 2-23.

4.7 Hydrology and Water Quality - City of Sacramento

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